Strong Poly(Vinyl Alcohol) (PVA)/Bamboo Charcoal (BC) Nanocomposite Films with Particle Size Effect

Abstract

In this paper, bamboo charcoals (BCs) were considered as alternative ecofriendly and sustainable carbon-based nanoparticles because of their good affinity with water-soluble biopolymer poly(vinyl alcohol) (PVA) to achieve strong PVA/BC nanocomposites. Two different types of BC particles, namely microdiameter bamboo charcoals (MBCs) and nanodiameter bamboo charcoals (NBCs) were successfully fabricated by the solution casting method. Nanofiller reinforcement effect was investigated from BC particle size and dispersion, morphological structures, and interfacial interactions between BCs and PVA matrices. Overall, the addition of NBCs yields increasingly higher mechanical properties of PVA/BC nanocomposites when compared with that of MBCs. The maximum enhancements in tensile moduli of nanocomposites were achieved up to 123% and 100% with the inclusion of 10 wt % NBCs and MBCs, respectively, whereas corresponding tensile strengths were improved by 110% and 72% with the incorporation of 3 wt % NBCs and MBCs accordingly, as opposed to those of PVA. Such findings obtained may be attributed to more uniform BC particle dispersion in PVA/BC nanocomposites and better interfacial interactions between BCs and PVA matrices. Tensile moduli of PVA/BC nanocomposites were predicted by Halpin−Tsai model and combined Mori-Tanaka model and laminate theory in both BC well-aligned and randomly oriented states, suggesting that the introduction of effective volume fractions of randomly oriented BCs led to the best modulus estimation. This study confirms the necessity of using BCs to replace conventional carbon-based nanofillers for developing more economical and eco-friendly nanocomposites.

Elastic Behavior of Nanophases in Polyvinyl Alcohol (PVA)/Bamboo Charcoal (BC) Nanocomposite Films

“…The variation of crystalline phase width is attributed to different orientation of semicrystalline stack Frontiers in Materials | www.frontiersin.orgbundles for the designated section (Panaitescu et al, 2013). Elastic modulus of bulk PVA films was about 2.08 GPa at a macroscopic level (Mousa and Dong, 2018b), which is less than that of local PVA nanoscaled regions based on AFM. Such a phenomenon is mainfested when nanomechanical properties are compared with those of bulk composites (Gu et al, 2010;Niu et al, 2016).…”

“…Bamboo charcoal (BC) nanoparticles was purchased from US Research Nanomaterials, Inc. Co., USA with specific surface area and average particle diameter being 624.81 m 2 /g and 69.43 nm, respectively (Mousa and Dong, 2018b). PVA powders (commercial grade: MFCD00081922) were obtained from Sigma Aldrich Pty.…”

“…Typical procedure for the fabrication of PVA /BC nanocomposite films was mentioned in details in our previous work (Mousa and Dong, 2018b). Briefly, PVA solution was obtained by dissolving 10 g PVA pellets in 190 ml deionized water via vigorous magnetic stirring at 90 • C for 3 h. In the meantime, BC suspension was prepared separately by blending particles in deionized water under mechanical mixing at 40 • C for 2 h, and then followed by ultra-sonication for 1 h at 25 kHz and 40 • C. Moreover, BC aqueous suspensions were gradually added in a dropwise manner into PVA solutions, which was simultaneously subjected to mechanical mixing at 40 • C for 2 h. Then, such a mixture was stirred at 90 • C for 1 h prior to the following sonication for 30 min to achieve uniform BC dispersion.…”

“…Briefly, PVA solution was obtained by dissolving 10 g PVA pellets in 190 ml deionized water via vigorous magnetic stirring at 90 • C for 3 h. In the meantime, BC suspension was prepared separately by blending particles in deionized water under mechanical mixing at 40 • C for 2 h, and then followed by ultra-sonication for 1 h at 25 kHz and 40 • C. Moreover, BC aqueous suspensions were gradually added in a dropwise manner into PVA solutions, which was simultaneously subjected to mechanical mixing at 40 • C for 2 h. Then, such a mixture was stirred at 90 • C for 1 h prior to the following sonication for 30 min to achieve uniform BC dispersion. The optimum BC content of 3 wt% was chosen according to our previously determined results (Mousa and Dong, 2018b) in the manufacture of final PVA/BC nanocomposites. Homogeneous PVA/BC solution was cast into a glass petri dish subjected further drying in an air-circulating oven at 40 • C until nanocomposite thin films (thickness: ∼0.8 mm) were peeled off.…”

“…In our previous work (Mousa and Dong, 2018b), very strong PVA nanocomposite films with the incorporation of BC nanoparticles were prepared at different BC contents of 0, 3, 5, and 10 wt% with the average particle diameter of 69.43 nm. The maximum increase of tensile strength of such nanocomposites was achieved by 110% with the reinforcement of 3 wt% BC nanoparticles as opposed to that of neat PVA at 70.32 MPa.…”